Idiopathic Interstitial Pneumonias

Question 1

Idiopathic Pulmonary Fibrosis - what is the pathologic diagnosis

Answer 1

Usual interstitial pneumonia (UIP)

Question 2

UIP - radiologic features

Answer 2

• low lung volumes, subpleural reticular opacities, macrocystic honeycombing, and traction bronchiectasis, the extent of which increases from the apex to the bases of the lung

Question 3

NSIP - which category of diseases is this the most common pulmonary manifestion of?

Answer 3

collagen vascular disease

Question 4

NSIP - what are the radiographic findings

Answer 4

• Ground-glass opacities (almost always bilateral), irregular linear or reticular opacities, micronodules, consolidation, microcystic honeycombing
• key imaging finding (not always seen but very specific) is sparing of immediate subpleural lung. This feature is NOT seen in UIP, and can be seen in both cellular and fibrotic NSIP.

Question 5

Cryptogenic Organizing Pneumonia - what is the pathologic pattern?

Answer 5

Organizing pneumonia

Question 6

Cryptogenic Organizing Pneumonia - what is the radiographic appearance? What relatively specific sign can be seen?

Answer 6

• Brief Review: Patchy, peripheral or peribronchial, basal predominance, sometimes sparing of subpleural space, migration tendency http://www.evernote.com/l/AiIycaPpU65P7Z2I3qG24JHvPVT83aliRBs/
• Lung opacities varies from ground glass to consolidation; in the latter, air bronchograms and mild cylindrical bronchial dilatation are a common finding (41). These opacities have a tendency to migrate, changing location and size, even without treatment (42). They are of variable size, ranging from a few centimeters to an entire lobe.
• reverse halo sign (also known as the atoll sign) is relatively specific for OP and features a central lucency surrounded by a ground glass halo.

reverse halo sign should not be confused with the halo sign that is typical of invasive aspergillus, which shows a central opacity with peripheral ground glass.

Question 7

Respiratory Bronchiolitis Interstitial Lung Disease - radiographic appearance

Answer 7

• centrilobular nodules and patchy ground glass opacities. In contrast to NSIP, the distribution of ground glass in RB-ILD is more random than the peripherally predominant pattern of NSIP.
• CT: Diffuse or upper lung predominance
• CT High Res: Centrilobular nodules, patchy ground-glass opacities, bronchial wall thickening

Question 8

Desquamative Interstitial Pneumonia - strong clinical correlate and radiographic appearance

Answer 8

Strongly associated with cigarette smoking and is considered to represent the end of a spectrum of RB-ILD

• diffuse basal-predominant patchy or subpleural ground glass opacification, more extensive than RB-ILD. Although the predominant abnormality is ground glass, a few cysts may also be present.
• Brief Review
• CT High Res: Ground-glass opacities, irregular linear or reticular opacities, sometimes cysts
• CT: Apicobasal gradient, peripheral predominance
• At high-resolution CT, DIP is characterized by diffuse ground-glass opacities, which correlate histologically with the spatially homogeneous intraalveolar accumulation of macrophages and thickening of alveolar septa (Fig 21) (58). Usually, there is a peripheral and lower lung lobe predominance (Fig 22) (59). Other frequent CT findings include spatially limited irregular linear opacities and small cystic spaces, which are indicative of fibrotic changes (Fig 23) (3). Despite differences in the CT appearance of RB-ILD and DIP, imaging findings may overlap and may be indistinguishable from each other. To improve diagnostic accuracy, lung biopsy is required in all cases of suspected RB-ILD or DIP (3).

Question 9

Lymphoid Interstitial Pneumonia - what diseases is it commonly associated with. What are the radiographic findings?

Answer 9

• diffuse or lower-lobe predominant ground glass. Scattered thin-walled perivascular cysts are often present, which are thought to be due to air trapping from peribronchiolar cellular debris.
• CT: Basilar predominance or diffuse
• CT High Res: Ground-glass opacities, perivascular cysts, septal thickening, centrilobular nodules
• Same thing, more depth:
  
  • In contrast to the subpleural, lower lung cystic changes in UIP, the cysts of LIP are usually within the lung parenchyma throughout the mid lung zones and presumably result from air trapping due to peribronchiolar cellular infiltration (64). In combination with groundglass opacities, these cysts are highly suggestive of LIP.

Question 10

Acute Interstitial Pneumonia - what is the clinical syndrome and what is the primary cause?

Answer 10

ARDS. Caused by surfactant destruction.

Question 11

AIP - what are the two phases and their associated radiographic findings

Answer 11

• Brief
  
  • CT: Lower lung predominance, symmetric, bilateral
  • CT High Res: Exudative phase shows groundglass opacities, airspace consolidation; organizing phase shows bronchial dilatation, architectural distortion
• More Depth
  
  • Similar to those of acute respiratory distress syndrome; however, patients with AIP are more likely to have a symmetric, bilateral distribution with a lower lobe predominance (Fig 28)
  • Early phase of AIP, ground-glass opacities are the dominant CT pattern and reflect the presence of alveolar septal edema and hyaline membranes (Fig 29) (69). Areas of consolidation are also present but are usually less extensive and limited to the dependent area of the lung (71). In the early phase, airspace consolidation results from intraalveolar edema and hemorrhage.
  • Late phase of AIP, architectural distortion, traction bronchiectasis, and hon eycombing are the most striking CT features and are more severe in the nondependent areas of the lung (Fig 30) (72,73).